Computed tomographic evaluation of canal shape instrumented by different kinematics rotary nickel-titanium systems.

INTRODUCTION This study evaluated the effects of 2 different kinematics rotary nickel-titanium (NiTi) systems, Twisted File (TF), a continuous rotation full-sequence system, and WaveOne (WO), a reciprocating single-file system, on transportation, curvature, and volumetric changes of curved root canals by using cone-beam computed tomography. METHODS Forty mesiobuccal canals of mandibular molars with angle of curvature ranging from 25°-35° were divided according to the NiTi rotary system used in canal preparation into 2 groups of 20 samples each, TF group and WO group. Canals were scanned by using an i-CAT cone-beam computed tomography scanner before and after instrumentation to evaluate canal transportation at coronal, middle, and apical thirds, canal curvature, and volumetric changes. The significance level was set at P ≤ .05. RESULTS TF system recorded significantly lower mean of canal transportation than WO group at all canal thirds (apical P = .034, middle P = .003, and coronal P = .012). In both groups the apical third recorded the significantly least amount of transportation (P < .05). There was no significant difference between the 2 groups in canal curvature and volumetric changes after instrumentation (P > .05). CONCLUSIONS Both TF and WO NiTi systems can be safely used to the full working length, resulting in satisfactory preservation of the original canal shape.